US8654041B2 - Organic light emitting display device having more uniform luminance and method of driving the same - Google Patents

Organic light emitting display device having more uniform luminance and method of driving the same Download PDF

Info

Publication number
US8654041B2
US8654041B2 US12/603,556 US60355609A US8654041B2 US 8654041 B2 US8654041 B2 US 8654041B2 US 60355609 A US60355609 A US 60355609A US 8654041 B2 US8654041 B2 US 8654041B2
Authority
US
United States
Prior art keywords
transistor
light emitting
scan
organic light
voltage
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Fee Related, expires
Application number
US12/603,556
Other versions
US20100127956A1 (en
Inventor
Chul-Kyu Kang
Sang-Moo Choi
Keum-Nam Kim
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Samsung Display Co Ltd
Original Assignee
Samsung Display Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Samsung Display Co Ltd filed Critical Samsung Display Co Ltd
Assigned to SAMSUNG MOBILE DISPLAY CO., LTD. reassignment SAMSUNG MOBILE DISPLAY CO., LTD. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: CHOI, SANG-MOO, Kang, Chul-Kyu, KIM, KEUM-NAM
Publication of US20100127956A1 publication Critical patent/US20100127956A1/en
Assigned to SAMSUNG DISPLAY CO., LTD. reassignment SAMSUNG DISPLAY CO., LTD. MERGER (SEE DOCUMENT FOR DETAILS). Assignors: SAMSUNG MOBILE DISPLAY CO., LTD.
Application granted granted Critical
Publication of US8654041B2 publication Critical patent/US8654041B2/en
Expired - Fee Related legal-status Critical Current
Adjusted expiration legal-status Critical

Links

Images

Classifications

    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/22—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources
    • G09G3/30—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels
    • G09G3/32—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED]
    • G09G3/3208—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED] organic, e.g. using organic light-emitting diodes [OLED]
    • G09G3/3225—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED] organic, e.g. using organic light-emitting diodes [OLED] using an active matrix
    • G09G3/3233—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED] organic, e.g. using organic light-emitting diodes [OLED] using an active matrix with pixel circuitry controlling the current through the light-emitting element
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10D—INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
    • H10D18/00—Thyristors
    • H10D18/40—Thyristors with turn-on by field effect 
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10D—INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
    • H10D84/00—Integrated devices formed in or on semiconductor substrates that comprise only semiconducting layers, e.g. on Si wafers or on GaAs-on-Si wafers
    • H10D84/101—Integrated devices comprising main components and built-in components, e.g. IGBT having built-in freewheel diode
    • H10D84/131—Thyristors having built-in components
    • H10D84/138—Thyristors having built-in components the built-in components being FETs
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2300/00—Aspects of the constitution of display devices
    • G09G2300/08—Active matrix structure, i.e. with use of active elements, inclusive of non-linear two terminal elements, in the pixels together with light emitting or modulating elements
    • G09G2300/0809—Several active elements per pixel in active matrix panels
    • G09G2300/0819—Several active elements per pixel in active matrix panels used for counteracting undesired variations, e.g. feedback or autozeroing
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2300/00—Aspects of the constitution of display devices
    • G09G2300/08—Active matrix structure, i.e. with use of active elements, inclusive of non-linear two terminal elements, in the pixels together with light emitting or modulating elements
    • G09G2300/0809—Several active elements per pixel in active matrix panels
    • G09G2300/0842—Several active elements per pixel in active matrix panels forming a memory circuit, e.g. a dynamic memory with one capacitor
    • G09G2300/0852—Several active elements per pixel in active matrix panels forming a memory circuit, e.g. a dynamic memory with one capacitor being a dynamic memory with more than one capacitor
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2310/00—Command of the display device
    • G09G2310/02—Addressing, scanning or driving the display screen or processing steps related thereto
    • G09G2310/0243—Details of the generation of driving signals
    • G09G2310/0251—Precharge or discharge of pixel before applying new pixel voltage
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2310/00—Command of the display device
    • G09G2310/02—Addressing, scanning or driving the display screen or processing steps related thereto
    • G09G2310/0262—The addressing of the pixel, in a display other than an active matrix LCD, involving the control of two or more scan electrodes or two or more data electrodes, e.g. pixel voltage dependent on signals of two data electrodes
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2320/00—Control of display operating conditions
    • G09G2320/04—Maintaining the quality of display appearance
    • G09G2320/043—Preventing or counteracting the effects of ageing

Definitions

  • the present invention relates to an organic light emitting display device and a method of driving the same.
  • Flat panel display devices include liquid crystal display devices, field emission display devices, plasma display panels, and organic light emitting display devices, among others.
  • the organic light emitting display device displays images using organic light emitting diodes that emit light through the recombination of electrons and holes.
  • the organic light emitting display device has a fast response time and is driven with low power consumption.
  • FIG. 1 is a circuit diagram of a conventional pixel of an organic light emitting display device.
  • transistors included in the pixel are NMOS transistors.
  • the conventional pixel 4 of the organic light emitting display device includes an organic light emitting diode OLED and a pixel circuit 2 connected to a data line Dm and a scan line Sn to control the organic light emitting diode OLED.
  • An anode electrode of the organic light emitting diode OLED is coupled to the pixel circuit 2 , and a cathode electrode thereof is coupled to a second power source ELVSS.
  • the organic light emitting diode OLED emits light having luminance corresponding to current supplied from the pixel circuit 2 .
  • the pixel circuit 2 controls an amount of current supplied to the organic light emitting diode OLED corresponding to a data signal supplied to a data line Dm when a scan signal is supplied to a scan line Sn.
  • the pixel circuit 2 includes a second transistor M 2 (i.e., a driving transistor) coupled between a first power source ELVDD and the organic light emitting diode OLED; a first transistor M 1 coupled between the second transistor M 2 and the data line Dm, with a gate electrode coupled to the scan line Sn; and a storage capacitor Cst coupled between a gate electrode and a second electrode of the second transistor M 2 .
  • a gate electrode of the first transistor M 1 is coupled to the scan line Sn, and a first electrode thereof is coupled to the data line Dm.
  • a second electrode of the first transistor M 1 is coupled to one terminal of the storage capacitor Cst.
  • the first electrode is either a source or a drain electrode, and the second electrode is the other electrode different from the first electrode.
  • the first electrode is a drain electrode, the second electrode is a source electrode.
  • the gate electrode of the second transistor M 2 is coupled to the one terminal of the storage capacitor Cst, and a first electrode thereof is coupled to the first power source ELVDD.
  • the second electrode of the second transistor M 2 is coupled to the other terminal of the storage capacitor Cst and the anode electrode of the organic light emitting diode OLED.
  • the second transistor M 2 controls an amount of current flowing from the first power source ELVDD through the organic light emitting diode OLED to the second power source ELVSS, the amount of current corresponding to the voltage stored in the storage capacitor Cst.
  • One terminal of the storage capacitor Cst is coupled to the gate electrode of the second transistor M 2 , and the other terminal thereof is coupled to the anode electrode of the organic light emitting diode OLED. A voltage corresponding to a data signal is charged into the storage capacitor Cst.
  • the conventional pixel 4 displays an image having a predetermined luminance by supplying current to the organic light emitting diode OLED corresponding to the voltage charged in the storage capacitor Cst.
  • images having uniform luminance are very difficult to display due to the threshold voltage variation of the second transistor M 2 .
  • Threshold voltages of second transistors M 2 in respective pixels 4 are different from each other, and the respective pixels 4 generate light having different luminance in response to a same data signal. Therefore, images having uniform luminance cannot be displayed.
  • exemplary embodiments of the present invention provide an organic light emitting display device which may compensate for a threshold voltage of a driving transistor and a method of driving the same.
  • An aspect of an exemplary embodiment of the present invention provides an organic light emitting display device including: a scan driver for sequentially supplying a scan signal through scan lines; a data driver for supplying an initial power through data lines during a first period of a time period when the scan signal is supplied through a corresponding scan line of the scan lines, and for supplying data signals to the data lines during a second period of the time period when the scan signal is supplied through the corresponding scan line, the second period following the first period; and pixels at crossing regions of the scan lines and the data lines, wherein a pixel coupled to an i-th (“i” is a natural number) scan line of the scan lines and a j-th (“j” is a natural number) data line of the data lines from among the pixels includes: an organic light emitting diode having a cathode electrode coupled to a second power source; a first transistor for controlling current flowing through the organic light emitting diode; a second transistor coupled to the j-th data line and a second node, the second transistor
  • a voltage of the data signals may be equal to or higher than a voltage of the reference power source.
  • a voltage of the initial power may be higher than a voltage of the data signal.
  • the organic light emitting display device may further include a second capacitor coupled in parallel with the third transistor between the first node and the second node.
  • An aspect of another exemplary embodiment of the present invention provides a method of driving an organic light emitting display device, including: supplying a reference power to a gate electrode of the driving transistor when a scan signal is supplied; supplying an initial power to a second terminal of the first capacitor through a data line during a first period of a time period when the scan signal is supplied; supplying a data signal to the second terminal of the first capacitor through the data line during a second period of the time period when the scan signal is supplied, the second period following the first period, wherein a voltage at the anode electrode of the organic light emitting diode is obtained by subtracting a threshold voltage of the driving transistor from the reference power; and supplying current to the organic light emitting diode by coupling the gate electrode of the driving transistor to the second terminal of the first capacitor.
  • An aspect of yet another exemplary embodiment of the present invention provides a pixel of an organic light emitting display device coupled to a scan line for supplying a scan signal and a data line for supplying a data signal, including: an organic light emitting diode coupled to a second power source; a first transistor coupled between the organic light emitting diode and a first power source, the first transistor for controlling current flowing through the organic light emitting diode in accordance with the data signal; a second transistor coupled to the data line for supplying the data signal when the scan signal is supplied; a third transistor coupled between the second transistor and a gate electrode of the first transistor; a fourth transistor coupled between the gate electrode of the first transistor and a reference power source; and a first capacitor coupled between the second transistor and the organic light emitting diode; wherein the second transistor and the fourth transistor concurrently turn on and off, and wherein the third transistor is turned off when the second transistor and the fourth transistor are turned on.
  • a desired current may be supplied to an organic light emitting diode regardless of a threshold voltage of a driving transistor. Accordingly, an image having uniform luminance may be displayed.
  • FIG. 1 is a circuit diagram of a pixel of a conventional organic light emitting display device.
  • FIG. 2 is a schematic block diagram of an organic light emitting display device according to an embodiment of the present invention.
  • FIG. 3 is a circuit diagram of a pixel according to a first embodiment of the present invention.
  • FIG. 4 is a waveform diagram illustrating a method of driving the pixel shown in FIG. 3 .
  • FIG. 5 is a graph showing current of an organic light emitting diode, corresponding to a change in voltage of a data signal in the pixel shown in FIG. 3 .
  • FIG. 6 is a circuit diagram of a pixel according to a second embodiment of the present invention.
  • FIG. 7 is a waveform diagram illustrating a method of driving the pixel shown in FIG. 6 .
  • FIG. 8 is a circuit diagram showing a structure in which transistors are converted into PMOS transistors in the pixel shown in FIG. 3 .
  • first element when a first element is described as being coupled to a second element, the first element may be directly coupled to the second element, or may be indirectly coupled to the second element via one or more additional elements. Further, some of the elements that are not essential to the complete understanding of the invention are omitted for clarity. Also, like reference numerals refer to like elements throughout.
  • FIG. 2 is a schematic block diagram of an organic light emitting display device according to an embodiment of the present invention.
  • the organic light emitting display device includes pixels 140 coupled to scan lines S 1 to Sn+1 and data lines D 1 to Dm; a scan driver 110 driving the scan lines S 1 to Sn+1; a data driver 120 driving the data lines D 1 to Dm; and a timing controller 150 controlling the scan and data drivers 110 and 120 .
  • the scan driver 110 receives a scan driving control signal SCS from the timing controller 150 .
  • the scan driver 110 generates a scan signal and sequentially supplies the generated scan signal to the scan lines S 1 to Sn+1.
  • the data driver 120 receives a data driving control signal DCS supplied from the timing controller 150 .
  • the data driver 120 supplies an initial power source to the data lines D 1 to Dm during a first period of a time period when a scan signal (e.g., a high scan signal) is supplied, and supplies a data signal to the data lines D 1 to Dm during a second period after the first period.
  • a scan signal e.g., a high scan signal
  • the voltage of the initial power source is set higher than that of the data signal.
  • the timing controller 150 generates a data driving control signal DCS and a scan driving control signal SCS in response to synchronization signals supplied from the outside.
  • the data driving control signal DCS generated from the timing controller 150 is supplied to the data driver 120
  • the scan driving control signal SCS generated from the timing controller 150 is supplied to the scan driver 110 .
  • the timing controller 150 also supplies data Data supplied from the outside to the data driver 120 .
  • a display unit 130 receives a first power source ELVDD, a second power source ELVSS and a reference power source Vref supplied from the outside, and supplies them to each of the pixels 140 .
  • Each of the pixels 140 receiving the first power source ELVDD, the second power source ELVSS and the reference power source Vref generates light in response to the data signals.
  • the voltage of the first power source ELVDD is set higher than that of the second power source ELVSS so that a current (e.g., a predetermined current) is supplied to the organic light emitting diodes.
  • a voltage of the reference power source Vref is set equal to or lower than that of the data signal.
  • a pixel 140 positioned in an i-th (“i” is a natural number) horizontal line is coupled to an i-th scan line and an (i+1)-th scan line, as well as a j-th (“j” is a natural number) data line.
  • the pixel 140 includes a plurality of transistors, which may be NMOS transistors, and supplies a current which is compensated for the threshold voltage of a driving transistor to a corresponding organic light emitting diode. In other embodiments, some or all of the plurality of transistors may be PMOS transistors.
  • FIG. 3 is a circuit diagram of a pixel according to a first embodiment of the present invention. For convenience of illustration, FIG. 3 shows a pixel positioned on an n-th horizontal line and coupled to an m-th data line Dm.
  • the pixel 140 includes an organic light emitting diode OLED and a pixel circuit 142 coupled to the data line Dm and the scan lines Sn and Sn+1 to control the organic light emitting diode OLED.
  • An anode electrode of the organic light emitting diode OLED is coupled to the pixel circuit 142 , and a cathode electrode thereof is coupled to a second power source ELVSS.
  • the organic light emitting diode OLED generates light having a luminance (e.g., a predetermined luminance) corresponding to current supplied from the pixel circuit 142 .
  • the pixel circuit 142 When a scan signal is supplied through the n-th scan line Sn, the pixel circuit 142 supplies a voltage corresponding to a data signal supplied through the data line Dm and a threshold voltage of a first transistor M 1 to be charged in a first capacitor C 1 .
  • the pixel circuit 142 supplies current corresponding to the charged voltage to the organic light emitting diode OLED.
  • the pixel circuit 142 includes first to fourth transistors M 1 to M 4 , and first and second capacitors C 1 and C 2 .
  • a gate electrode of the first transistor M 1 is coupled to a first node N 1 , and a first electrode thereof is coupled to a first power source ELVDD.
  • a second electrode of the first transistor M 1 is coupled to an anode electrode of the organic light emitting diode OLED at a third node N 3 .
  • a gate electrode of the second transistor M 2 is coupled to the n-th scan line Sn, and a first electrode thereof is coupled to the data line Dm.
  • a second electrode of the second transistor M 2 is coupled to a second node N 2 .
  • a gate electrode of the third transistor M 3 is coupled to the (n+1)-th scan line Sn+1, and a first electrode thereof is coupled to the second node N 2 .
  • a second electrode of the third transistor M 3 is coupled to the first node N 1 (i.e., the gate electrode of the first transistor M 1 ).
  • the third transistor M 3 is turned on to allow the first node N 1 to be electrically coupled to the second node N 2 .
  • the third transistor M 3 is in a turned-off state while the second transistor M 2 is turned on.
  • a gate electrode of the fourth transistor M 4 is coupled to the n-th scan line Sn, and a first electrode thereof is coupled to a reference power source Vref.
  • a second electrode of the fourth transistor M 4 is coupled to the first node N 1 .
  • the first and second capacitors C 1 and C 2 are coupled in series between the first and third nodes N 1 and N 3 .
  • a common node of the first and second capacitors C 1 and C 2 is coupled to a common node (i.e., the second node N 2 ) of the second and third transistors M 2 and M 3 .
  • the second capacitor C 2 and the third transistor M 3 are coupled in parallel between the first and second node N 1 and N 2 .
  • FIG. 4 is a waveform diagram illustrating a method of driving the pixel shown in FIG. 3 .
  • a scan signal (e.g., a high scan signal) is supplied through the n-th scan line Sn, and an initial power source Vint is supplied through the data line Dm during a first period of a time period when the scan signal is supplied through the n-th scan line Sn.
  • the second and fourth transistors M 2 and M 4 are turned on.
  • the initial power source Vint is supplied to the second node N 2 .
  • the fourth transistor M 4 is turned on, the voltage of the reference power source Vref is supplied to the first node N 1 .
  • the voltage of the reference power source Vref is set as a low voltage at which the first transistor M 1 is turned off.
  • a data signal is supplied through the data line Dm during a second period after the first period, and accordingly the voltage at the second node N 2 is dropped to the voltage of the data signal.
  • the voltage at the third node N 3 is also dropped due to coupling of the first capacitor C 1 .
  • the first transistor M 1 is turned on, and the voltage at the third node N 3 is raised to a voltage obtained by subtracting the threshold voltage of the first transistor M 1 from the voltage of the reference power source Vref.
  • the voltage of the initial power source Vint is set to allow the voltage at the third node N 3 to be dropped to a lower voltage than that of the reference power source Vref.
  • Vdata refers to a voltage of the data signal.
  • a scan signal (e.g., the high scan signal) is supplied through the (n+1)-th scan line Sn+1, and the first node N 1 is electrically coupled to the second node N 2 .
  • the voltage applied between the terminals of the second capacitor C 2 is set as 0V, and the voltage between the gate and source electrodes of the first transistor M 1 is set as a voltage charged into the first capacitor C 1 . That is, the voltage of the first transistor M 1 is set based on Equation 1:
  • Vgs ( M 1) V data ⁇ V ref+ Vth ( M 1) (1)
  • An amount of current flowing through the organic light emitting diode OLED is set using the voltage Vgs of the first transistor M 1 based on Equation 2:
  • the current flowing through the organic light emitting diode OLED is determined by a voltage difference between the voltage Vdata of the data signal and the reference power source Vref.
  • the reference power source Vref is a fixed voltage
  • the current flowing through the organic light emitting diode OLED is determined by the data signal.
  • Equation 3 a voltage range of the first power source ELVDD, the reference power source Vref and the voltage Vdata of the data signal is set based on Equation 3:
  • Equation 3 ELVDD>V data ⁇ V ref (3)
  • the voltage of the reference voltage Vref is a fixed voltage having a low voltage at which current does not flow through the organic light emitting diode OLED, and Vdata is changed corresponding to a gray level expressed as the voltage of the data signal.
  • a gray level is realized by the voltage Vdata of the data signal and the voltage of the reference power source. Therefore, the voltage Vdata of the data signal is set equal to or higher than that of the reference power source Vref.
  • FIG. 5 is a graph showing current flowing through an organic light emitting diode, corresponding to a voltage of a data signal.
  • the current flowing through the organic light emitting diode OLED is changed depending on a change in voltage Vdata of the data signal. That is, in the present invention, an amount of current flowing through the organic light emitting diode OLED is changed corresponding to a change in voltage of the data signal. Accordingly, a desired gray level can be expressed.
  • FIG. 6 is a circuit diagram of a pixel according to a second embodiment of the present invention.
  • elements identical to those of FIG. 3 are provided with the same reference numerals, and their detailed descriptions will be omitted.
  • the pixel 140 ′ is coupled to a light emission control line En.
  • light emission control lines E 1 to En are positioned parallel with scan lines S 1 to Sn and formed in respective horizontal lines. That is, the light emission control lines E 1 to En are arranged parallel with the scan lines S 1 to Sn.
  • a light emission control signal supplied through an i-th (“i” is a natural number) light emission control line Ei is supplied to overlap with a scan signal supplied through an i-th scan line Si.
  • the scan signal sequentially supplied through the scan lines S 1 to Sn may be set as a voltage (e.g., a high level voltage) at which transistors may be turned on
  • the light emission control signal sequentially supplied through the light emission control lines E 1 to En may be set as a voltage (e.g., a low level voltage) at which the transistors may be turned off.
  • a gate electrode of a third transistor M 3 ′ included in the pixel circuit 142 ′ is coupled to the light emission control line En, and a first electrode of the third transistor M 3 ′ is coupled to a second node N 2 .
  • a second electrode of the third transistor M 3 ′ is coupled to a first node N 1 .
  • a first capacitor C 1 ′ is coupled between the first electrode of the third transistor M 3 ′ (i.e., the second node N 2 ) and a third node N 3 .
  • the electric connection of the third transistor M 3 ′ and the first capacitor C 1 ′ is set different from that in the pixel 140 .
  • the second capacitor C 2 has been removed in the pixel 140 ′.
  • FIG. 7 is a waveform diagram illustrating a method of driving the pixel shown in FIG. 6 .
  • a scan signal (e.g., a high scan signal) is supplied through the n-th scan line Sn, and an initial power source Vint is supplied through a data line Dm during a first period of a time period when the scan signal is supplied through the n-th scan line Sn.
  • a light emission control signal (e.g., a low light emission control signal) is supplied through the n-th light emission control line En during the period when the scan signal is supplied through the n-th scan line Sn.
  • the third transistor M 3 ′ is turned off.
  • the scan signal is supplied through the n-th scan line Sn, second and fourth transistors M 2 and M 4 are turned on.
  • the second transistor M 2 is turned on, the initial power source Vint supplied from the data line Dm is supplied to the second node N 2 .
  • the fourth transistor M 4 is turned on, the voltage of a reference voltage Vref is supplied to the first node N 1 .
  • a data signal is supplied through the data line Dm during a second period after the first period, and accordingly, the voltage at the second node N 2 is dropped to the voltage Vdata of the data signal.
  • the voltage at the third node N 3 is also dropped due to coupling of the first capacitor C 1 ′.
  • the first transistor M 1 is turned on, and the voltage at the third node N 3 is raised to a voltage obtained by subtracting the threshold voltage of the first transistor M 1 from the voltage of the reference power source Vref.
  • a voltage set based on Equation 1 is charged into the first capacitor C 1 ′.
  • the supply of the scan signal through the n-th scan line Sn is stopped (e.g., the scan signal is turned low), and the second and fourth transistors M 2 and M 4 are turned off.
  • the supply of the light emission control signal through the n-th light emission control line En is also stopped (e.g., the light emission control signal is turned high), and the third transistor M 3 ′ is turned on.
  • the third transistor M 3 ′ is turned on, the second node N 2 is electrically coupled to the first node N 1 .
  • the first transistor M 1 supplies current corresponding to the voltage charged into the first capacitor C 1 ′ to an organic light emitting diode OLED.
  • a current set based on Equation 2 is therefore supplied to the organic light emitting diode OLED. That is, in the pixel 140 ′ according to the second embodiment of the present invention, a desired current may be supplied to the organic light emitting diode OLED regardless of the threshold voltage of the first transistor M 1 .
  • the transistors are NMOS transistors.
  • the present invention is not limited thereto.
  • the transistors of the pixel shown in FIG. 3 may instead be PMOS transistors, as shown in, for example, FIG. 8 .
  • operations are substantially similar, except that the polarities of the waveforms shown in FIG. 4 are reversed.

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Computer Hardware Design (AREA)
  • General Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • Control Of El Displays (AREA)
  • Electroluminescent Light Sources (AREA)
  • Control Of Indicators Other Than Cathode Ray Tubes (AREA)

Abstract

An organic light emitting display device includes a scan driver for sequentially supplying a scan signal through scan lines; a data driver for supplying an initial power through data lines during a first period of a time period when the scan signal is supplied through a corresponding scan line of the scan lines, and for supplying data signals to the data lines during a second period of the time period when the scan signal is supplied through the corresponding scan line, the second period following the first period; and pixels at crossing regions of the scan lines and the data lines.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims priority to and the benefit of Korean Patent Application No. 10-2008-0118055, filed on Nov. 26, 2008, in the Korean Intellectual Property Office, the entire content of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an organic light emitting display device and a method of driving the same.
2. Description of Related Art
Recently, various types of flat panel display devices having reduced weight and volume in comparison to cathode ray tubes have been developed. Flat panel display devices include liquid crystal display devices, field emission display devices, plasma display panels, and organic light emitting display devices, among others.
Among these flat panel display devices, the organic light emitting display device displays images using organic light emitting diodes that emit light through the recombination of electrons and holes. The organic light emitting display device has a fast response time and is driven with low power consumption.
FIG. 1 is a circuit diagram of a conventional pixel of an organic light emitting display device. In FIG. 1, transistors included in the pixel are NMOS transistors.
Referring to FIG. 1, the conventional pixel 4 of the organic light emitting display device includes an organic light emitting diode OLED and a pixel circuit 2 connected to a data line Dm and a scan line Sn to control the organic light emitting diode OLED.
An anode electrode of the organic light emitting diode OLED is coupled to the pixel circuit 2, and a cathode electrode thereof is coupled to a second power source ELVSS. The organic light emitting diode OLED emits light having luminance corresponding to current supplied from the pixel circuit 2.
The pixel circuit 2 controls an amount of current supplied to the organic light emitting diode OLED corresponding to a data signal supplied to a data line Dm when a scan signal is supplied to a scan line Sn. To this end, the pixel circuit 2 includes a second transistor M2 (i.e., a driving transistor) coupled between a first power source ELVDD and the organic light emitting diode OLED; a first transistor M1 coupled between the second transistor M2 and the data line Dm, with a gate electrode coupled to the scan line Sn; and a storage capacitor Cst coupled between a gate electrode and a second electrode of the second transistor M2.
A gate electrode of the first transistor M1 is coupled to the scan line Sn, and a first electrode thereof is coupled to the data line Dm. A second electrode of the first transistor M1 is coupled to one terminal of the storage capacitor Cst. Here, the first electrode is either a source or a drain electrode, and the second electrode is the other electrode different from the first electrode. For example, if the first electrode is a drain electrode, the second electrode is a source electrode. When a scan signal is supplied to the first transistor M1 from the scan line Sn, the first transistor M1 is turned on, and a data signal supplied from the data line Dm is supplied to the storage capacitor Cst. At this time, a voltage corresponding to the data signal is charged into the storage capacitor Cst.
The gate electrode of the second transistor M2 is coupled to the one terminal of the storage capacitor Cst, and a first electrode thereof is coupled to the first power source ELVDD. The second electrode of the second transistor M2 is coupled to the other terminal of the storage capacitor Cst and the anode electrode of the organic light emitting diode OLED. The second transistor M2 controls an amount of current flowing from the first power source ELVDD through the organic light emitting diode OLED to the second power source ELVSS, the amount of current corresponding to the voltage stored in the storage capacitor Cst.
One terminal of the storage capacitor Cst is coupled to the gate electrode of the second transistor M2, and the other terminal thereof is coupled to the anode electrode of the organic light emitting diode OLED. A voltage corresponding to a data signal is charged into the storage capacitor Cst.
The conventional pixel 4 displays an image having a predetermined luminance by supplying current to the organic light emitting diode OLED corresponding to the voltage charged in the storage capacitor Cst. However, in such a conventional organic light emitting display device, images having uniform luminance are very difficult to display due to the threshold voltage variation of the second transistor M2.
Threshold voltages of second transistors M2 in respective pixels 4 are different from each other, and the respective pixels 4 generate light having different luminance in response to a same data signal. Therefore, images having uniform luminance cannot be displayed.
SUMMARY OF THE INVENTION
Accordingly, exemplary embodiments of the present invention provide an organic light emitting display device which may compensate for a threshold voltage of a driving transistor and a method of driving the same.
An aspect of an exemplary embodiment of the present invention provides an organic light emitting display device including: a scan driver for sequentially supplying a scan signal through scan lines; a data driver for supplying an initial power through data lines during a first period of a time period when the scan signal is supplied through a corresponding scan line of the scan lines, and for supplying data signals to the data lines during a second period of the time period when the scan signal is supplied through the corresponding scan line, the second period following the first period; and pixels at crossing regions of the scan lines and the data lines, wherein a pixel coupled to an i-th (“i” is a natural number) scan line of the scan lines and a j-th (“j” is a natural number) data line of the data lines from among the pixels includes: an organic light emitting diode having a cathode electrode coupled to a second power source; a first transistor for controlling current flowing through the organic light emitting diode; a second transistor coupled to the j-th data line and a second node, the second transistor being on when the scan signal is supplied through the i-th scan line; a third transistor coupled between a first node coupled to a gate electrode of the first transistor and the second node, the third transistor being off when the second transistor is on; a fourth transistor coupled between the first node and a reference power source, the fourth transistor being on when the scan signal is supplied through the i-th scan line; and a first capacitor coupled between the second node and an anode electrode of the organic light emitting diode.
A voltage of the data signals may be equal to or higher than a voltage of the reference power source. A voltage of the initial power may be higher than a voltage of the data signal. The organic light emitting display device may further include a second capacitor coupled in parallel with the third transistor between the first node and the second node.
An aspect of another exemplary embodiment of the present invention provides a method of driving an organic light emitting display device, including: supplying a reference power to a gate electrode of the driving transistor when a scan signal is supplied; supplying an initial power to a second terminal of the first capacitor through a data line during a first period of a time period when the scan signal is supplied; supplying a data signal to the second terminal of the first capacitor through the data line during a second period of the time period when the scan signal is supplied, the second period following the first period, wherein a voltage at the anode electrode of the organic light emitting diode is obtained by subtracting a threshold voltage of the driving transistor from the reference power; and supplying current to the organic light emitting diode by coupling the gate electrode of the driving transistor to the second terminal of the first capacitor.
An aspect of yet another exemplary embodiment of the present invention provides a pixel of an organic light emitting display device coupled to a scan line for supplying a scan signal and a data line for supplying a data signal, including: an organic light emitting diode coupled to a second power source; a first transistor coupled between the organic light emitting diode and a first power source, the first transistor for controlling current flowing through the organic light emitting diode in accordance with the data signal; a second transistor coupled to the data line for supplying the data signal when the scan signal is supplied; a third transistor coupled between the second transistor and a gate electrode of the first transistor; a fourth transistor coupled between the gate electrode of the first transistor and a reference power source; and a first capacitor coupled between the second transistor and the organic light emitting diode; wherein the second transistor and the fourth transistor concurrently turn on and off, and wherein the third transistor is turned off when the second transistor and the fourth transistor are turned on.
In an organic light emitting display device and a method of driving the same, a desired current may be supplied to an organic light emitting diode regardless of a threshold voltage of a driving transistor. Accordingly, an image having uniform luminance may be displayed.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings illustrate exemplary embodiments of the present invention, and, together with the description, serve to explain the principles of the present invention.
FIG. 1 is a circuit diagram of a pixel of a conventional organic light emitting display device.
FIG. 2 is a schematic block diagram of an organic light emitting display device according to an embodiment of the present invention.
FIG. 3 is a circuit diagram of a pixel according to a first embodiment of the present invention.
FIG. 4 is a waveform diagram illustrating a method of driving the pixel shown in FIG. 3.
FIG. 5 is a graph showing current of an organic light emitting diode, corresponding to a change in voltage of a data signal in the pixel shown in FIG. 3.
FIG. 6 is a circuit diagram of a pixel according to a second embodiment of the present invention.
FIG. 7 is a waveform diagram illustrating a method of driving the pixel shown in FIG. 6.
FIG. 8 is a circuit diagram showing a structure in which transistors are converted into PMOS transistors in the pixel shown in FIG. 3.
 DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS
Hereinafter, certain exemplary embodiments according to the present invention will be described with reference to the accompanying drawings. Here, when a first element is described as being coupled to a second element, the first element may be directly coupled to the second element, or may be indirectly coupled to the second element via one or more additional elements. Further, some of the elements that are not essential to the complete understanding of the invention are omitted for clarity. Also, like reference numerals refer to like elements throughout.
FIG. 2 is a schematic block diagram of an organic light emitting display device according to an embodiment of the present invention.
Referring to FIG. 2, the organic light emitting display device according to the embodiment of the present invention includes pixels 140 coupled to scan lines S1 to Sn+1 and data lines D1 to Dm; a scan driver 110 driving the scan lines S1 to Sn+1; a data driver 120 driving the data lines D1 to Dm; and a timing controller 150 controlling the scan and data drivers 110 and 120.
The scan driver 110 receives a scan driving control signal SCS from the timing controller 150. The scan driver 110 generates a scan signal and sequentially supplies the generated scan signal to the scan lines S1 to Sn+1.
The data driver 120 receives a data driving control signal DCS supplied from the timing controller 150. The data driver 120 supplies an initial power source to the data lines D1 to Dm during a first period of a time period when a scan signal (e.g., a high scan signal) is supplied, and supplies a data signal to the data lines D1 to Dm during a second period after the first period. Here, the voltage of the initial power source is set higher than that of the data signal.
The timing controller 150 generates a data driving control signal DCS and a scan driving control signal SCS in response to synchronization signals supplied from the outside. The data driving control signal DCS generated from the timing controller 150 is supplied to the data driver 120, and the scan driving control signal SCS generated from the timing controller 150 is supplied to the scan driver 110. The timing controller 150 also supplies data Data supplied from the outside to the data driver 120.
A display unit 130 receives a first power source ELVDD, a second power source ELVSS and a reference power source Vref supplied from the outside, and supplies them to each of the pixels 140. Each of the pixels 140 receiving the first power source ELVDD, the second power source ELVSS and the reference power source Vref generates light in response to the data signals.
Here, the voltage of the first power source ELVDD is set higher than that of the second power source ELVSS so that a current (e.g., a predetermined current) is supplied to the organic light emitting diodes. A voltage of the reference power source Vref is set equal to or lower than that of the data signal.
Meanwhile, a pixel 140 positioned in an i-th (“i” is a natural number) horizontal line is coupled to an i-th scan line and an (i+1)-th scan line, as well as a j-th (“j” is a natural number) data line. The pixel 140 includes a plurality of transistors, which may be NMOS transistors, and supplies a current which is compensated for the threshold voltage of a driving transistor to a corresponding organic light emitting diode. In other embodiments, some or all of the plurality of transistors may be PMOS transistors.
FIG. 3 is a circuit diagram of a pixel according to a first embodiment of the present invention. For convenience of illustration, FIG. 3 shows a pixel positioned on an n-th horizontal line and coupled to an m-th data line Dm.
Referring to FIG. 3, the pixel 140 according to the first embodiment of the present invention includes an organic light emitting diode OLED and a pixel circuit 142 coupled to the data line Dm and the scan lines Sn and Sn+1 to control the organic light emitting diode OLED.
An anode electrode of the organic light emitting diode OLED is coupled to the pixel circuit 142, and a cathode electrode thereof is coupled to a second power source ELVSS. The organic light emitting diode OLED generates light having a luminance (e.g., a predetermined luminance) corresponding to current supplied from the pixel circuit 142.
When a scan signal is supplied through the n-th scan line Sn, the pixel circuit 142 supplies a voltage corresponding to a data signal supplied through the data line Dm and a threshold voltage of a first transistor M1 to be charged in a first capacitor C1. When a scan signal is supplied through the (n+1)-th scan line Sn+1, the pixel circuit 142 supplies current corresponding to the charged voltage to the organic light emitting diode OLED. To this end, the pixel circuit 142 includes first to fourth transistors M1 to M4, and first and second capacitors C1 and C2.
A gate electrode of the first transistor M1 is coupled to a first node N1, and a first electrode thereof is coupled to a first power source ELVDD. A second electrode of the first transistor M1 is coupled to an anode electrode of the organic light emitting diode OLED at a third node N3.
A gate electrode of the second transistor M2 is coupled to the n-th scan line Sn, and a first electrode thereof is coupled to the data line Dm. A second electrode of the second transistor M2 is coupled to a second node N2. When a scan signal is supplied through the n-th scan line Sn, the second transistor M2 is turned on to allow the data line Dm to be electrically coupled to the second node N2.
A gate electrode of the third transistor M3 is coupled to the (n+1)-th scan line Sn+1, and a first electrode thereof is coupled to the second node N2. A second electrode of the third transistor M3 is coupled to the first node N1 (i.e., the gate electrode of the first transistor M1). When a scan signal is supplied through the (n+1)-th scan line Sn+1, the third transistor M3 is turned on to allow the first node N1 to be electrically coupled to the second node N2. The third transistor M3 is in a turned-off state while the second transistor M2 is turned on.
A gate electrode of the fourth transistor M4 is coupled to the n-th scan line Sn, and a first electrode thereof is coupled to a reference power source Vref. A second electrode of the fourth transistor M4 is coupled to the first node N1. When a scan signal is supplied through the n-th scan line Sn, the fourth transistor M4 is turned on to supply the voltage of the reference power source Vref to the first node N1.
The first and second capacitors C1 and C2 are coupled in series between the first and third nodes N1 and N3. A common node of the first and second capacitors C1 and C2 is coupled to a common node (i.e., the second node N2) of the second and third transistors M2 and M3. Here, the second capacitor C2 and the third transistor M3 are coupled in parallel between the first and second node N1 and N2.
FIG. 4 is a waveform diagram illustrating a method of driving the pixel shown in FIG. 3.
Operations of the pixel will be described in detail in conjunction with FIGS. 3 and 4. First, a scan signal (e.g., a high scan signal) is supplied through the n-th scan line Sn, and an initial power source Vint is supplied through the data line Dm during a first period of a time period when the scan signal is supplied through the n-th scan line Sn.
When the scan signal is supplied through the n-th scan line Sn, the second and fourth transistors M2 and M4 are turned on. When the second transistor M2 is turned on, the initial power source Vint is supplied to the second node N2. When the fourth transistor M4 is turned on, the voltage of the reference power source Vref is supplied to the first node N1. Here, the voltage of the reference power source Vref is set as a low voltage at which the first transistor M1 is turned off.
Thereafter, a data signal is supplied through the data line Dm during a second period after the first period, and accordingly the voltage at the second node N2 is dropped to the voltage of the data signal. When the voltage at the second node N2 is dropped, the voltage at the third node N3 is also dropped due to coupling of the first capacitor C1. At this time, the first transistor M1 is turned on, and the voltage at the third node N3 is raised to a voltage obtained by subtracting the threshold voltage of the first transistor M1 from the voltage of the reference power source Vref. To this end, when the data signal is supplied through the data line Dm, the voltage of the initial power source Vint is set to allow the voltage at the third node N3 to be dropped to a lower voltage than that of the reference power source Vref.
At this time, a voltage of Vdata−Vref is charged in the second capacitor C2, and a voltage of Vdata−Vref+Vth is charged in the first capacitor C1. Here, Vdata refers to a voltage of the data signal.
Thereafter, the supply of the scan signal through the n-th scan line Sn is stopped (e.g., the scan signal turns low), and the second and fourth transistors M2 and M4 are turned off. A scan signal (e.g., the high scan signal) is supplied through the (n+1)-th scan line Sn+1, and the first node N1 is electrically coupled to the second node N2. In this case, the voltage applied between the terminals of the second capacitor C2 is set as 0V, and the voltage between the gate and source electrodes of the first transistor M1 is set as a voltage charged into the first capacitor C1. That is, the voltage of the first transistor M1 is set based on Equation 1:
Equation 1
Vgs(M1)=Vdata−Vref+Vth(M1)  (1)
An amount of current flowing through the organic light emitting diode OLED is set using the voltage Vgs of the first transistor M1 based on Equation 2:
Equation ⁢ ⁢ ⁢ 2 Ioled = ⁢ β ⁡ ( Vgs ⁡ ( M ⁢ ⁢ 1 ) - Vth ⁡ ( M ⁢ ⁢ 1 ) ) 2 = ⁢ β ⁢ { ( Vdata - Vref + Vth ⁡ ( M ⁢ ⁢ 1 ) ) - Vth ⁡ ( M ⁢ ⁢ 1 ) } 2 = ⁢ β ⁡ ( Vdata - Vref ) 2 ( 2 )
Referring to Equation 2, the current flowing through the organic light emitting diode OLED is determined by a voltage difference between the voltage Vdata of the data signal and the reference power source Vref. Here, since the reference power source Vref is a fixed voltage, the current flowing through the organic light emitting diode OLED is determined by the data signal.
Meanwhile, a voltage range of the first power source ELVDD, the reference power source Vref and the voltage Vdata of the data signal is set based on Equation 3:
Equation 3
ELVDD>Vdata≧Vref  (3)
The voltage of the reference voltage Vref is a fixed voltage having a low voltage at which current does not flow through the organic light emitting diode OLED, and Vdata is changed corresponding to a gray level expressed as the voltage of the data signal. Here, a gray level is realized by the voltage Vdata of the data signal and the voltage of the reference power source. Therefore, the voltage Vdata of the data signal is set equal to or higher than that of the reference power source Vref.
FIG. 5 is a graph showing current flowing through an organic light emitting diode, corresponding to a voltage of a data signal.
Referring to FIG. 5, the current flowing through the organic light emitting diode OLED is changed depending on a change in voltage Vdata of the data signal. That is, in the present invention, an amount of current flowing through the organic light emitting diode OLED is changed corresponding to a change in voltage of the data signal. Accordingly, a desired gray level can be expressed.
FIG. 6 is a circuit diagram of a pixel according to a second embodiment of the present invention. In FIG. 6, elements identical to those of FIG. 3 are provided with the same reference numerals, and their detailed descriptions will be omitted.
Referring to FIG. 6, the pixel 140′ according to the second embodiment of the present invention is coupled to a light emission control line En. Here, light emission control lines E1 to En are positioned parallel with scan lines S1 to Sn and formed in respective horizontal lines. That is, the light emission control lines E1 to En are arranged parallel with the scan lines S1 to Sn. A light emission control signal supplied through an i-th (“i” is a natural number) light emission control line Ei is supplied to overlap with a scan signal supplied through an i-th scan line Si.
Meanwhile, the scan signal sequentially supplied through the scan lines S1 to Sn may be set as a voltage (e.g., a high level voltage) at which transistors may be turned on, and the light emission control signal sequentially supplied through the light emission control lines E1 to En may be set as a voltage (e.g., a low level voltage) at which the transistors may be turned off.
A gate electrode of a third transistor M3′ included in the pixel circuit 142′ is coupled to the light emission control line En, and a first electrode of the third transistor M3′ is coupled to a second node N2. A second electrode of the third transistor M3′ is coupled to a first node N1.
A first capacitor C1′ is coupled between the first electrode of the third transistor M3′ (i.e., the second node N2) and a third node N3.
When comparing the pixel 140′ with the pixel 140 shown in FIG. 3, the electric connection of the third transistor M3′ and the first capacitor C1′ is set different from that in the pixel 140. When comparing the pixel 140′ with the pixel 140 shown in FIG. 3, the second capacitor C2 has been removed in the pixel 140′.
FIG. 7 is a waveform diagram illustrating a method of driving the pixel shown in FIG. 6.
Operations of the pixel will be described in detail in conjunction with FIGS. 6 and 7. First, a scan signal (e.g., a high scan signal) is supplied through the n-th scan line Sn, and an initial power source Vint is supplied through a data line Dm during a first period of a time period when the scan signal is supplied through the n-th scan line Sn. A light emission control signal (e.g., a low light emission control signal) is supplied through the n-th light emission control line En during the period when the scan signal is supplied through the n-th scan line Sn.
When the light emission control signal is supplied through the n-th light emission control line En, the third transistor M3′ is turned off. When the scan signal is supplied through the n-th scan line Sn, second and fourth transistors M2 and M4 are turned on. When the second transistor M2 is turned on, the initial power source Vint supplied from the data line Dm is supplied to the second node N2. When the fourth transistor M4 is turned on, the voltage of a reference voltage Vref is supplied to the first node N1.
Thereafter, a data signal is supplied through the data line Dm during a second period after the first period, and accordingly, the voltage at the second node N2 is dropped to the voltage Vdata of the data signal. When the voltage at the second node N2 is dropped, the voltage at the third node N3 is also dropped due to coupling of the first capacitor C1′. At this time, the first transistor M1 is turned on, and the voltage at the third node N3 is raised to a voltage obtained by subtracting the threshold voltage of the first transistor M1 from the voltage of the reference power source Vref. Here, a voltage set based on Equation 1 is charged into the first capacitor C1′.
Thereafter, the supply of the scan signal through the n-th scan line Sn is stopped (e.g., the scan signal is turned low), and the second and fourth transistors M2 and M4 are turned off. The supply of the light emission control signal through the n-th light emission control line En is also stopped (e.g., the light emission control signal is turned high), and the third transistor M3′ is turned on. When the third transistor M3′ is turned on, the second node N2 is electrically coupled to the first node N1. Accordingly, the first transistor M1 supplies current corresponding to the voltage charged into the first capacitor C1′ to an organic light emitting diode OLED. A current set based on Equation 2 is therefore supplied to the organic light emitting diode OLED. That is, in the pixel 140′ according to the second embodiment of the present invention, a desired current may be supplied to the organic light emitting diode OLED regardless of the threshold voltage of the first transistor M1.
Meanwhile, it has been described in FIGS. 3 and 6 that the transistors are NMOS transistors. However, the present invention is not limited thereto. For example, the transistors of the pixel shown in FIG. 3 may instead be PMOS transistors, as shown in, for example, FIG. 8. In this case, operations are substantially similar, except that the polarities of the waveforms shown in FIG. 4 are reversed.
While the present invention has been described in connection with certain exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but is instead intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims, and equivalents thereof.

Claims (15)

What is claimed is:
1. An organic light emitting display device comprising:
a scan driver for sequentially supplying a scan signal through scan lines;
a data driver for supplying an initial power through data lines during a first period of a time period when the scan signal is supplied through a corresponding scan line of the scan lines, and for supplying data signals to the data lines during a second period of the time period when the scan signal is supplied through the corresponding scan line, the second period following the first period; and
pixels at crossing regions of the scan lines and the data lines,
wherein a pixel coupled to an i-th (“i” is a natural number) scan line of the scan lines and a j-th (“j” is a natural number) data line of the data lines from among the pixels comprises:
an organic light emitting diode having a cathode electrode coupled to a second power source;
a first transistor for controlling current flowing through the organic light emitting diode;
a second transistor coupled to the j-th data line and a second node, the second transistor being on when the scan signal is supplied through the i-th scan line;
a third transistor coupled to the second node and coupled directly to a first node at a gate electrode of the first transistor, the third transistor being off when the second transistor is on;
a fourth transistor coupled directly between the first node and a reference power source, the fourth transistor being on when the scan signal is supplied through the i-th scan line, such that the second transistor and the fourth transistor concurrently turn on and off; and
a first capacitor coupled between the second node and an anode electrode of the organic light emitting diode.
2. The organic light emitting display device of claim 1, wherein a voltage of the data signals is equal to or higher than a voltage of the reference power source.
3. The organic light emitting display device of claim 1, wherein a voltage of the initial power is higher than a voltage of the data signals.
4. The organic light emitting display device of claim 1, further comprising a second capacitor coupled in parallel with the third transistor between the first node and the second node.
5. The organic light emitting display device of claim 4, wherein, the third transistor is turned on when the scan signal is supplied through an (i+1)-th scan line of the scan lines.
6. The organic light emitting display device of claim 1, wherein the scan driver sequentially supplies a light emission control signal through light emission control lines that are parallel to the scan lines.
7. The organic light emitting display device of claim 6, wherein the light emission control signal supplied through an i-th light emission control line of the light emission control lines overlaps with the scan signal supplied through the i-th scan line, the light emission control signal being a voltage at which a corresponding one of the transistors is turned off.
8. The organic light emitting display device of claim 7, wherein a gate electrode of the third transistor is coupled to the i-th light emission control line.
9. A method of driving an organic light emitting display device provided with a driving transistor supplying current to an anode electrode of an organic light emitting diode and a first capacitor having a first terminal coupled to the anode electrode of the organic light emitting diode, the method comprising:
supplying a reference power to a gate electrode of the driving transistor when a scan signal is supplied;
supplying an initial power to a second terminal of the first capacitor through a data line during a first period of a time period when the scan signal is supplied and the reference power is supplied to the gate electrode of the driving transistor;
supplying a data signal to the second terminal of the first capacitor through the data line during a second period of the time period when the scan signal is supplied and the reference power is supplied to the gate electrode of the driving transistor, the second period following the first period, wherein a voltage at the anode electrode of the organic light emitting diode is obtained by subtracting a threshold voltage of the driving transistor from the reference power; and
supplying current to the organic light emitting diode by directly coupling the gate electrode of the driving transistor to the second terminal of the first capacitor.
10. The method of claim 9, wherein a voltage of the data signal is equal to or higher than a voltage of the reference power.
11. The method of claim 9, wherein a voltage of the initial power is higher than a voltage of the data signal.
12. A pixel of an organic light emitting display device coupled to a scan line for supplying a scan signal and a data line for supplying a data signal, comprising:
an organic light emitting diode coupled to a second power source;
a first transistor coupled between the organic light emitting diode and a first power source, the first transistor for controlling current flowing through the organic light emitting diode in accordance with the data signal;
a second transistor coupled to the data line for supplying the data signal when the scan signal is supplied;
a third transistor coupled to the second transistor and coupled directly to a gate electrode of the first transistor;
a fourth transistor coupled directly between the gate electrode of the first transistor and a reference power source; and
a first capacitor coupled between the second transistor and the organic light emitting diode;
wherein the second transistor and the fourth transistor concurrently turn on and off, and wherein the third transistor is turned off when the second transistor and the fourth transistor are turned on; and
wherein a data driver is configured to supply an initial power through the data line in a first period of a time period when the scan signal is supplied, and to supply the data signal through the data line in a second period of the time period when the scan signal is supplied, the second period following the first period.
13. The pixel of claim 12, wherein a voltage of the initial power is higher than a voltage of the data signal.
14. The pixel of claim 12, wherein a voltage of the data signal is equal to or higher than a voltage of the reference power source.
15. The pixel of claim 12, further comprising a second capacitor coupled in parallel with the third transistor between the second transistor and the gate electrode of the first transistor.
US12/603,556 2008-11-26 2009-10-21 Organic light emitting display device having more uniform luminance and method of driving the same Expired - Fee Related US8654041B2 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
KR1020080118055A KR100986915B1 (en) 2008-11-26 2008-11-26 Organic light emitting display device and driving method thereof
KR10-2008-0118055 2008-11-26

Publications (2)

Publication Number Publication Date
US20100127956A1 US20100127956A1 (en) 2010-05-27
US8654041B2 true US8654041B2 (en) 2014-02-18

Family

ID=41467120

Family Applications (1)

Application Number Title Priority Date Filing Date
US12/603,556 Expired - Fee Related US8654041B2 (en) 2008-11-26 2009-10-21 Organic light emitting display device having more uniform luminance and method of driving the same

Country Status (5)

Country Link
US (1) US8654041B2 (en)
EP (1) EP2192571B1 (en)
JP (1) JP5064421B2 (en)
KR (1) KR100986915B1 (en)
CN (1) CN101739947B (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20170372663A1 (en) * 2016-01-29 2017-12-28 Shenzhen China Star Optoelectronics Technology Co., Ltd. Pixel Compensation Circuit, Method And Flat Display Device
US10504444B2 (en) 2018-03-09 2019-12-10 Au Optronics Corporation Pixel circuit
US11013087B2 (en) 2012-03-13 2021-05-18 Semiconductor Energy Laboratory Co., Ltd. Light-emitting device having circuits and method for driving the same

Families Citing this family (32)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100986915B1 (en) 2008-11-26 2010-10-08 삼성모바일디스플레이주식회사 Organic light emitting display device and driving method thereof
KR101056302B1 (en) 2009-03-26 2011-08-11 삼성모바일디스플레이주식회사 Organic light emitting display
KR101008482B1 (en) 2009-04-17 2011-01-14 삼성모바일디스플레이주식회사 Pixel and organic light emitting display device using same
KR101351416B1 (en) * 2010-05-18 2014-01-14 엘지디스플레이 주식회사 Pixel circuit of voltage compensation type of active matrix organic light emitting diode display device
KR101666586B1 (en) * 2010-06-22 2016-10-14 엘지디스플레이 주식회사 Driving appratus of organic light emitting diode display device and method for driving the same
KR101666589B1 (en) * 2010-07-02 2016-10-14 엘지디스플레이 주식회사 Organic light emitting diode display device and method for driving the same
KR101748857B1 (en) * 2010-10-28 2017-06-20 삼성디스플레이 주식회사 Organic Light Emitting Display Device
KR101765778B1 (en) * 2010-12-06 2017-08-08 삼성디스플레이 주식회사 Organic Light Emitting Display Device
KR101528147B1 (en) 2011-10-14 2015-06-12 엘지디스플레이 주식회사 Light emitting display device
CN103123773B (en) * 2011-11-21 2016-08-03 上海天马微电子有限公司 Amoled pixel driving circuit
TWI449016B (en) * 2012-06-07 2014-08-11 Au Optronics Corp Pixel driving circuit, driving method thereof and display panel
CN102982767B (en) * 2012-12-10 2015-02-25 京东方科技集团股份有限公司 Pixel unit driving circuit, driving method and display device
CN103218970B (en) * 2013-03-25 2015-03-25 京东方科技集团股份有限公司 Active matrix organic light emitting diode (AMOLED) pixel unit, driving method and display device
KR102028995B1 (en) * 2013-06-28 2019-10-07 엘지디스플레이 주식회사 Organic light emitting diode display device and method for driving the same
CN103413520B (en) * 2013-07-30 2015-09-02 京东方科技集团股份有限公司 Pixel-driving circuit, display device and image element driving method
JP2015045830A (en) 2013-08-29 2015-03-12 三星ディスプレイ株式會社Ｓａｍｓｕｎｇ Ｄｉｓｐｌａｙ Ｃｏ．，Ｌｔｄ． Electro-optic device
JP2015045831A (en) 2013-08-29 2015-03-12 三星ディスプレイ株式會社Ｓａｍｓｕｎｇ Ｄｉｓｐｌａｙ Ｃｏ．，Ｌｔｄ． Electro-optic device
KR102135925B1 (en) * 2013-12-30 2020-07-20 엘지디스플레이 주식회사 Organic light emitting diode display device and mathod for manufacturing the same
CN104751777B (en) 2013-12-31 2017-10-17 昆山工研院新型平板显示技术中心有限公司 Image element circuit, pixel and AMOLED display device and its driving method including the pixel
US10607542B2 (en) 2013-12-31 2020-03-31 Kunshan New Flat Panel Display Technology Center Co., Ltd. Pixel circuit, pixel, and AMOLED display device comprising pixel and driving method thereof
JP6586951B2 (en) * 2014-05-14 2019-10-09 ソニー株式会社 Display device, driving method, and electronic apparatus
KR102356593B1 (en) 2015-01-14 2022-01-28 삼성디스플레이 주식회사 Organic light-emitting display apparatus and driving method thereof
KR102345405B1 (en) * 2015-10-29 2021-12-31 엘지디스플레이 주식회사 Organic Light Emitting Display
KR102458968B1 (en) * 2016-05-18 2022-10-27 삼성디스플레이 주식회사 Display device
KR102605174B1 (en) 2016-12-19 2023-11-22 엘지디스플레이 주식회사 Light emitting diode display apparatus
KR102746145B1 (en) * 2016-12-21 2024-12-27 삼성디스플레이 주식회사 Display device and driving method thereof
KR102635824B1 (en) * 2016-12-30 2024-02-08 엘지디스플레이 주식회사 Organic light emitting display panel and organic light emitting display apparatus using the same
KR102348062B1 (en) * 2017-04-04 2022-01-10 삼성디스플레이 주식회사 Organic light emitting display device and driving method thereof
TWI706400B (en) * 2019-08-13 2020-10-01 友達光電股份有限公司 Pixel circuit and driving method for the same
TWI697884B (en) * 2019-08-20 2020-07-01 友達光電股份有限公司 Pixel circuit
CN111477179B (en) * 2020-05-20 2021-10-22 京东方科技集团股份有限公司 A pixel driving circuit, a driving method thereof, and a display device
CN119068820A (en) * 2023-05-30 2024-12-03 京东方科技集团股份有限公司 Display device, display panel, pixel circuit and driving method thereof

Citations (26)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20040026723A1 (en) 2002-07-31 2004-02-12 Seiko Epson Corporation System and methods for driving an electro-optical device
KR20050025510A (en) 2003-09-08 2005-03-14 삼성에스디아이 주식회사 Pixel driving circuit and method for organic electroluminescent display
WO2005036515A1 (en) 2003-10-09 2005-04-21 Koninklijke Philips Electronics N.V. Electroluminescent display device with scrolling addressing
US20050140605A1 (en) 2003-11-24 2005-06-30 Jin-Tae Jung Image display device and driving method thereof
JP2006113586A (en) 2004-10-08 2006-04-27 Samsung Sdi Co Ltd Light emitting display device and pixel circuit
CA2557713A1 (en) 2005-09-13 2006-11-26 Ignis Innovation Inc. Compensation technique for luminance degradation in electro-luminance devices
US20060267884A1 (en) * 2005-05-25 2006-11-30 Seiko Epson Corporation Light-emitting device, method for driving the same driving circuit and electronic apparatus
US20070024544A1 (en) * 2005-08-01 2007-02-01 Chung Bo Y Data driving circuits and driving methods of organic light emitting displays using the same
US20070126665A1 (en) 2005-12-02 2007-06-07 Semiconductor Energy Laboratory Co., Ltd. Semiconductor device, display device, and electronic device
JP2007140318A (en) 2005-11-22 2007-06-07 Sony Corp Pixel circuit
JP2007206590A (en) 2006-02-06 2007-08-16 Seiko Epson Corp Pixel circuit, driving method thereof, display device, and electronic apparatus
CN101075407A (en) 2006-05-18 2007-11-21 Lg.菲利浦Lcd株式会社 Pixel circuit of organic light emitting display
KR20070112714A (en) 2006-05-22 2007-11-27 소니 가부시끼 가이샤 Display device and driving method
KR20070118857A (en) 2006-06-13 2007-12-18 한양대학교 산학협력단 Organic EL element and driving method thereof
KR20080001482A (en) 2006-06-29 2008-01-03 엘지.필립스 엘시디 주식회사 Pixel circuit of organic light emitting display device
JP2008026467A (en) 2006-07-19 2008-02-07 Sony Corp Display device and method of driving same
WO2008075697A1 (en) 2006-12-20 2008-06-26 Canon Kabushiki Kaisha Light-emitting display device
KR20080062307A (en) 2006-12-29 2008-07-03 엘지디스플레이 주식회사 Organic light emitting diode display device and method of driving the same
CN101256732A (en) 2007-03-02 2008-09-03 三星Sdi株式会社 organic light emitting display
KR20080080754A (en) 2007-03-02 2008-09-05 삼성에스디아이 주식회사 Organic light emitting display
KR20080080755A (en) 2007-03-02 2008-09-05 삼성에스디아이 주식회사 Organic light emitting display
KR100858618B1 (en) 2007-04-10 2008-09-17 삼성에스디아이 주식회사 Organic light emitting display device and driving method thereof
KR20080084017A (en) 2007-03-14 2008-09-19 삼성에스디아이 주식회사 Pixel and organic light emitting display device using same and driving method thereof
JP2008241783A (en) 2007-03-26 2008-10-09 Sony Corp Display device and driving method thereof and electronic equipment
EP2192571A2 (en) 2008-11-26 2010-06-02 Samsung Mobile Display Co., Ltd. Organic light emitting display device and method of driving the same
US8294643B2 (en) * 2004-10-22 2012-10-23 Au Optronics Corp. Pixel of display

Patent Citations (31)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20040026723A1 (en) 2002-07-31 2004-02-12 Seiko Epson Corporation System and methods for driving an electro-optical device
KR20050025510A (en) 2003-09-08 2005-03-14 삼성에스디아이 주식회사 Pixel driving circuit and method for organic electroluminescent display
WO2005036515A1 (en) 2003-10-09 2005-04-21 Koninklijke Philips Electronics N.V. Electroluminescent display device with scrolling addressing
US20050140605A1 (en) 2003-11-24 2005-06-30 Jin-Tae Jung Image display device and driving method thereof
JP2006113586A (en) 2004-10-08 2006-04-27 Samsung Sdi Co Ltd Light emitting display device and pixel circuit
US8294643B2 (en) * 2004-10-22 2012-10-23 Au Optronics Corp. Pixel of display
US20060267884A1 (en) * 2005-05-25 2006-11-30 Seiko Epson Corporation Light-emitting device, method for driving the same driving circuit and electronic apparatus
US20070024544A1 (en) * 2005-08-01 2007-02-01 Chung Bo Y Data driving circuits and driving methods of organic light emitting displays using the same
US20070063932A1 (en) * 2005-09-13 2007-03-22 Arokia Nathan Compensation technique for luminance degradation in electro-luminance devices
CN101305409A (en) 2005-09-13 2008-11-12 伊格尼斯创新有限公司 Compensation technique for luminance degradation in electro-luminance devices
CA2557713A1 (en) 2005-09-13 2006-11-26 Ignis Innovation Inc. Compensation technique for luminance degradation in electro-luminance devices
JP2007140318A (en) 2005-11-22 2007-06-07 Sony Corp Pixel circuit
US20070126665A1 (en) 2005-12-02 2007-06-07 Semiconductor Energy Laboratory Co., Ltd. Semiconductor device, display device, and electronic device
JP2007206590A (en) 2006-02-06 2007-08-16 Seiko Epson Corp Pixel circuit, driving method thereof, display device, and electronic apparatus
CN101075407A (en) 2006-05-18 2007-11-21 Lg.菲利浦Lcd株式会社 Pixel circuit of organic light emitting display
US20070268217A1 (en) 2006-05-18 2007-11-22 Tae Joon Ahn Pixel circuit of organic light emitting display
KR20070112714A (en) 2006-05-22 2007-11-27 소니 가부시끼 가이샤 Display device and driving method
KR20070118857A (en) 2006-06-13 2007-12-18 한양대학교 산학협력단 Organic EL element and driving method thereof
KR20080001482A (en) 2006-06-29 2008-01-03 엘지.필립스 엘시디 주식회사 Pixel circuit of organic light emitting display device
JP2008026467A (en) 2006-07-19 2008-02-07 Sony Corp Display device and method of driving same
WO2008075697A1 (en) 2006-12-20 2008-06-26 Canon Kabushiki Kaisha Light-emitting display device
JP2008176287A (en) 2006-12-20 2008-07-31 Canon Inc Luminescent display device
KR20080062307A (en) 2006-12-29 2008-07-03 엘지디스플레이 주식회사 Organic light emitting diode display device and method of driving the same
KR20080080754A (en) 2007-03-02 2008-09-05 삼성에스디아이 주식회사 Organic light emitting display
KR20080080755A (en) 2007-03-02 2008-09-05 삼성에스디아이 주식회사 Organic light emitting display
US20080211747A1 (en) 2007-03-02 2008-09-04 Yangwan Kim Organic light emitting display
CN101256732A (en) 2007-03-02 2008-09-03 三星Sdi株式会社 organic light emitting display
KR20080084017A (en) 2007-03-14 2008-09-19 삼성에스디아이 주식회사 Pixel and organic light emitting display device using same and driving method thereof
JP2008241783A (en) 2007-03-26 2008-10-09 Sony Corp Display device and driving method thereof and electronic equipment
KR100858618B1 (en) 2007-04-10 2008-09-17 삼성에스디아이 주식회사 Organic light emitting display device and driving method thereof
EP2192571A2 (en) 2008-11-26 2010-06-02 Samsung Mobile Display Co., Ltd. Organic light emitting display device and method of driving the same

Non-Patent Citations (10)

* Cited by examiner, † Cited by third party
Title
European Patent Gazette dated May 16, 2012, for European Patent application 10157704.7, (1 page).
European Search Report dated May 7, 2010, for corresponding European Patent application 09176250.0, noting listed references in this IDS.
Japanese Office action dated Feb. 7, 2012, for corresponding Japanese Patent application 2009-021682, 1 page.
Japanese Office action dated Jul. 10, 2012, for corresponding Japanese Patent application 2009-021682, (3 pages).
Japanese Office action dated Mar. 13, 2012, for Japanese Patent application 2009-207021, (1 page).
KIPO Office action dated Jul. 18, 2011, for Korean Patent application 10-2009-0025841, (1 page).
KIPO Office action dated Sep. 6, 2010, for priority Korean Patent application 10-2008-0118055.
SIPO Patent Gazette dated Dec. 12, 2012, for corresponding Chinese Patent application 200910205439.7, with English translaiton of p. 1 only, (3 pages).
SIPO Patent Gazette dated Mar. 6, 2013, for Chinese Patent application 201010125570.5, with English translation of cover page only, (3 pages).
U.S. Office action dated Feb. 3, 2012, for cross reference U.S. Appl. No. 12/683,189, (10 pages).

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US11013087B2 (en) 2012-03-13 2021-05-18 Semiconductor Energy Laboratory Co., Ltd. Light-emitting device having circuits and method for driving the same
US20170372663A1 (en) * 2016-01-29 2017-12-28 Shenzhen China Star Optoelectronics Technology Co., Ltd. Pixel Compensation Circuit, Method And Flat Display Device
US9966005B2 (en) * 2016-01-29 2018-05-08 Shenzhen China Star Optoelectronics Technology Co., Ltd Pixel compensation circuit, method and flat display device
US10504444B2 (en) 2018-03-09 2019-12-10 Au Optronics Corporation Pixel circuit

Also Published As

Publication number Publication date
EP2192571B1 (en) 2017-08-23
CN101739947B (en) 2012-12-12
EP2192571A3 (en) 2010-06-09
JP2010128491A (en) 2010-06-10
CN101739947A (en) 2010-06-16
KR20100059318A (en) 2010-06-04
JP5064421B2 (en) 2012-10-31
KR100986915B1 (en) 2010-10-08
EP2192571A2 (en) 2010-06-02
US20100127956A1 (en) 2010-05-27

Similar Documents

Publication Publication Date Title
US8654041B2 (en) Organic light emitting display device having more uniform luminance and method of driving the same
US8907870B2 (en) Pixel and organic light emitting display device using the pixel
US8786587B2 (en) Pixel and organic light emitting display using the same
US8379004B2 (en) Pixel and organic light emitting display device using the same
KR101056302B1 (en) Organic light emitting display
US8446344B2 (en) Pixel and organic light emitting display device using the same
KR101142729B1 (en) Pixel and Organic Light Emitting Display Device Using the same
US8570249B2 (en) Pixel coupled to three horizontal lines and organic light emitting display device using the same
CN101533851B (en) Pixel and organic light emitting display using same
US8791889B2 (en) Pixel and organic light emitting display device using the same
US8638279B2 (en) Pixel and organic light emitting display device using the same
KR101765778B1 (en) Organic Light Emitting Display Device
US20110050741A1 (en) Organic light emitting display device and driving method thereof
US8319713B2 (en) Pixel and organic light emitting display using the same
US20100128014A1 (en) Pixel and organic light emitting display device using the same
US9047816B2 (en) Pixel and organic light emitting display device using the same
US8928642B2 (en) Pixel and organic light emitting display device using the same
US20110084959A1 (en) Pixel and organic light emitting display using the same

Legal Events

Date Code Title Description
AS Assignment

Owner name: SAMSUNG MOBILE DISPLAY CO., LTD., KOREA, REPUBLIC

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:KANG, CHUL-KYU;CHOI, SANG-MOO;KIM, KEUM-NAM;REEL/FRAME:023439/0623

Effective date: 20090921

AS Assignment

Owner name: SAMSUNG DISPLAY CO., LTD., KOREA, REPUBLIC OF

Free format text: MERGER;ASSIGNOR:SAMSUNG MOBILE DISPLAY CO., LTD.;REEL/FRAME:028884/0128

Effective date: 20120702

FEPP Fee payment procedure

Free format text: PAYOR NUMBER ASSIGNED (ORIGINAL EVENT CODE: ASPN); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY

FEPP Fee payment procedure

Free format text: MAINTENANCE FEE REMINDER MAILED (ORIGINAL EVENT CODE: REM.)

LAPS Lapse for failure to pay maintenance fees

Free format text: PATENT EXPIRED FOR FAILURE TO PAY MAINTENANCE FEES (ORIGINAL EVENT CODE: EXP.)

STCH Information on status: patent discontinuation

Free format text: PATENT EXPIRED DUE TO NONPAYMENT OF MAINTENANCE FEES UNDER 37 CFR 1.362

FP Lapsed due to failure to pay maintenance fee

Effective date: 20180218